Iwona Budziak, D. Karcz, M. Makowski
Oct 1, 2019
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Influential Citations
14
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Journal
Journal of Molecular Liquids
Abstract
Abstract The article presents the results of spectroscopic studies conducted on three compounds from the 1,3,4-thiadiazole group: 2-amino-5-phenyl-1,3,4-thiadiazole (TB), 2-amino-5-(2-hydroxyphenyl)-1,3,4-thiadiazole (TS), 2-amino-5-(2-hydroxy-5-sulfobenzoyl)-1,3,4-thiadiazole (TSF). The fluorescence emission spectra of the previously reported TS analogue revealed an interesting dual fluorescence effect in butanol. Depending on the structural composition of the resorcylic system, for the other analogues two partially overlapping emission bands or single emission bands were observed. Interpretation of the UV–Vis spectra, stationary fluorescence, RLS, as well as fluorescence lifetimes allowed us to correlate said effects with the phenomenon of specific molecular aggregation which, depending on the substituent, can induce the process related to charge transfer within the given molecule. The conducted calculations of dipole moment changes for the ground and excited state, as well as the [TD] DFT calculations confirmed our assumptions with regard to the experimental results. The described study was also the first to analyse fluorescence effects, for this particular group of analogues, relative to primarily the structural composition of the first substituent by the thiadiazole ring. The correlation between said fluorescence effects and earlier measurements conducted on analogues in from this group of compounds in various systems (liposomes, micelles, or crystals) also suggests the possibility of charge transfer (CT) dependant on the appropriate conformation of the molecule (with the -OH group on the side of the nitrogen atom in the thiadiazole ring). It should be emphasised that this type of fluorescence effects can be relatively easily identified with the use of fluorescence methods, which means that fluorophores from this group can be used as ideal fluorescence probes which continue to be in high demand in the context of biology/molecular medicine.